Tube bending device



Oct. 18, 1966 B. J. LANCE TUBE BENDING DEVICE Filed March 12, 1965 FIG.2

INVENTOR Bauer J lfl/VC'E F165 JWMQ W United States Patent f 3,279,236 TUBE BENDING DEVICE Bruce J; Lance, Paramount, Calif. (1460 Chase Drive, Corona, Calif.) Filed Man 12, l965,Ser. No. 439,387 2 Claims. (Cl. 72-396) The present invention relates generally to the automotive field, and more specifically to an apparatus for effecting a bend in tubing without appreciably distorting the transverse cross section thereof, particularly in the case of automotive exhaust pipes. This application is a continuation-in-part of my application entitled Apparatus for Forming Replacement Exhaust Pipes and Method of Using Same, Serial No. 159,604,- filed in the United States Patent Ofiice on December 15, 1961, now Patent No. 3,196,661, which issued July 27, 1965.

In said copending application an apparatus and method of using the same was disclosed by means of which a replacement exhaust pipe for any make of automobile and yearly model thereof may be quickly and easily fabricated from straight tubing stock. In using the apparatus disclosed in said copending application Serial No. 159,604, upon occasion it was found that in the bending of tubing a longitudinally extending crease developed in that part of the wall of the bend subjected to the greatest longitudinal deformation.

A primary object of the present invention is to provide improved jaws for use on the apparatus disclosed and claimed in said 'copending application, which jaws are of such internal configuration that the bends formed in tubing or pipe by the use thereof are substantially free of longitudinally extending creases.

These and other objects and advantages of the present invention will become apparent from the following description of a preferred form thereof, and from the accompanying drawings illustrating the same, in which:

FIGURE 1 is'a perspective view of an apparatus in which the dies are used to form bends in tubing without formation of longitudinally extending creases in the bends;

FIGURE 2 is a fragmentary transverse cross-sectional view of one of the improved jaws, taken on the line 2-2 of FIGURE 1;

FIGURE 3 is a transverse cross-sectional View of a longitudinally creased bend in a length of tubing which was formed without the use of one of the improved jaws hereinafter described; and

FIGURE 4 is a transverse section of a bend in tubing formed by use of the improved jaws.

FIGURE 1 is a perspective view of a portion of the device disclosed and claimed in said Patent No. 3,196,661, which includes a column A that has two identical jaws L and M which are pivotally supported on the upper forward portion thereof by means of two plates 18 and 20 respectively. Plates 18 and 20 are afiixed to the forward ends of two identical short shafts (not shown) that extend rearwardly through two identical bearings 24, one of which is shown in FIGURE 1. The bearings 24 are rigidly afiixed to column A by conventional means (not shown). Two arms 26, one of which is shown in FIG- URE 1, are affixed to the rear ends of the two shafts 22. Pins 28 extend transversely through the arms 26. The pins 28 engage the bifurcated ends 30 of two piston rods 32. The two piston rods 32 are longitudinally movable in two downwardly and outwardly extending cylinders 36, one of which cylinders is shown in FIGURE 1.

Eyes 38 are provided on the upper ends of cylinders 36 through which pins 40 extend, and these pins are supported by lugs 42 that project outwardly from the upper portion of column A. Fluid under pressure can be in- 3,279,236 Patented Oct. 18, 1966 troduced into the cylinders 36 through hoses 44, one of which is shown in FIGURE 1. The fluid so introduced tends to restrain downward pivotal movement of the jaws L and M. The means by which the fluid under pressure is so introduced is described in detail in said Patent No. 3,196,661.

Two transversely spaced, parallel grooves 52 and 54 are formed in each of the jaws L and M. The diameters of grooves 52 and 54 are different, with the groove 52 being used to bend tubing having an external diameter of.

1 /4", and the groove 54 being adapted to be used to bend tubing having an external diameter of 2".

The grooves 52 and 54 are generally semicircular, each of which has two longitudinally extending sections 57 and a lower longitudinally extending section 59, both of which have the same radius of curvature as that of the external surface of the tubing to be bent by the use thereof. Sections 57 and 59 in each of the grooves 52 and 54 are connected by two laterally spaced downwardly and inwardly extending straight sections 61 or chords, as best shown in FIGURE 2. i

A semi-circular pressure member 56 is centrally located relative to the jaws L and M when they are positioned as shown in FIGURE 1. Two semi-circular grooves 52' and 54' are formed in a pressure member 56, and these grooves are in vertical alignment with the grooves 52 and 54. The pressure member 56 is located on the lower end of a piston rod 58, the upper end of which is connected to a piston 60.

Piston 60 is slidably movable within the confines of a hydraulic cylinder 62 that has a lower end 64 which the piston rod 58 slidably and sealingly engages. The hydraulic cylinder 62 has a closed upper end 66 and two laterally spaced lugs 68 project upwardly therefrom. A horizontal pin '70 extends'through lugs 68 as well as through an outwardly extending part 72 of the upper portion of column A, to support the hydraulic cylinder 62 in a depending position. A hydraulic liquid under pressure can be discharged into the upper confines of the hydraulic cylinder 62 through a conduit 74 to force the piston 60, piston rod 58, and pressure member 56 downwardly. Likewise, w-hen fluid is permitted to escape through the conduit 74, fluid can be discharged into the lower confines of the cylinder 62 through a conduit 76 to force the piston 60, piston rod 58, and pressure member 56 upwardly to place the pressurememberin the position shown in FIGURE 1. v i i When fluid under pressure is discharged through the conduit 74 into the hydraulic cylinder 62, the piston 60, piston rod 58, and pressure member 56 are moved downwardly for either the groove 52' of the pressure member or groove 54' thereof to engage a desired portion of the tubing K, and as a downward force is applied to this engaged portion, the jaw L and M pivot outwardly away from one another to impart a curve of a desired degree to the portion of the tubing K situated between the pressure member 56 and the jaws. Jaws L and M resist this outward movement in opposite directions, and the degree of this resistance is dependent on the magnitude of the force exerted by the piston rods 32 and arms 26. The degree of resistance the piston rods 32 will exert on arms 26 is, of course, dependent on the pressure at which fluid is discharged to the upper confines of the cylinders 36.

Due to the pressure of hydraulic fluid in cylinders 36, the jaws L and M at all times tend to remain in the horizontal position shown in FIGURE 1. The flow of hydraulic fluid to and from the cylinder 62 is controlled by means disclosed in detail in said application Serial No. 159,604. The pressure of fluid in cylinder 62 must be sufiiciently great as to move member 56 downwardly with a force of such magnitude to overcome the pivotal resistance offered by the jaws L and M.

The use and operation of the invention are relatively simple. That lower portion of tubing K to be bent is disposed on the appropriate pair of grooves 52 or 54. Hydraulic fluid is maintained in cylinders 36 under sufficient pressure as to tend to restrain downward pivotal movement of the jaws L and M. The hydraulic fluid is then discharged into cylinder 62 under sufficient pressure as to move members 56 downwardly, with the portion of the tubing K between one of the grooves 52 or 54' and grooves 52 or 54 being bent as the jaws L and M pivot downwardly.

The straight sections 61 are closer radially to the longitudinal center line 65 of the grooves 52 and 54 than the sections 57 and 59. As a result, when the pressure member 56 moves downwardly, the lower semi-cylindrical portion of the tubing K in either groove 52 or 54 is first deformed to abut against the sections 61 and then deform to contact the sections 57 and 59. The transversely deformed tubing K has the shape shown in FIGURE 5. In this figure the portions of the tubing K in contact with the sections 57, 59 and 61 are identified by the same numerals but to which a prime has been added.

As tubing K is forced downwardly in the die X it deforms in such a manner that the lower ends of the portions 61 move upwardly and inwardly towards one another as the portions 59' move downwardly towards sections 59. Such movement shortens the horizontal distance between the lower ends of the portions 61', and causes the portions 59 to bow downwardly until they are in abutting contact with sections 59. This bowing effect counteracts any tendency of the portions 59' which are subject to maximum longitudinal elongation to form a longitudinally extending crease T along the center thereof as shown in FIGURE 3.

After the bending operation is completed, the pressure member 56 is moved upwardly with concurrent upward pivotal movement of the jaws L and M to positions where the tubing K can be advanced and another bend formed therein, or the bent tubing removed from the device.

Although the present invention is fully capable of achieving the objects and providing the advantages hereinbefore mentioned, it is to be understood that it is merely illustrative of the presently preferred embodiments thereof and I do not mean to be limited to the details of construction herein shown and described, other than as defined in the appended claims.

I claim:

1. In a machine for bending a length of tubing that includes a vertical column, two longitudinally aligned jaws pivotally supported from said column, means for tending to restrain downward pivotal movement of said jaws, a downwardly curved pressure-exerting member that has at least one groove of semi-circular transverse cross section formed in the lowermost surface thereof, means for moving said pressure-exerting member down wardly relative to said jaws with a force sufficient to overcome the resistance offered by said means for tending to restrain downward pivotal movement of said jaws, the improvement for bending said tubing, which improvement comprises two longitudinally aligned grooves of nonsemi-circular transverse cross section formed in the upper portions of said jaws that are in alignment with said groove in said pressure-exerting member and of such configuration as to bend said tubing without forming a longitudinally extending crease therein as said pressureexerting member is moved downwardly relative to said jaws to pivot the same downwardly and outwardly in opposite directions, with each of said grooves in said jaws being defined by:

(a) two upper transversely spaced, longitudinally extending arcuate sections;

(b) a lower concave longitudinally extending section;

and

(0) two straight transversely spaced longitudinally extending chord sections that extend downwardly and inwardly towards one another from the lower extremities of said upper arcuate sections to the upper extremities of said lower surface.

2. A machine as defined in claim 1 wherein said two upper arcuate surfaces and said lower concave surface have substantially the same radius of curvature as that of the external surface of said tubing that is being bent.

References Cited by the Examiner UNITED STATES PATENTS 1,948,474 2/1934 Meyer 72-396 2,455,138 11/1948 Perkins 72l59 2,690,782 10/1954 Tirone 72l'54 2,882,953 4/1959 Huet 72l59 2,887,141 5/1959 Bower et al 72-396 FOREIGN PATENTS 483,790 8/1953 Italy.

CHARLES W. LANHAM, Primary Examiner, R. D. GREFE, Assistant Examiner, 

1. IN A MACHINE FOR BENDING A LENGTH OF TUBING THAT INCLUDES A VERTICAL COLUMN, TWO LONGITUDINALLY ALIGNED JAWS PIVOTALLY SUPPORTED FROM SAID COLUMN, MEANS FOR TENDING, TO RESTRAIN DOWNWARD PIVOTAL MOVEMENT OF SAID JAWS, A DOWNWARDLY CURVED PRESSURE-EXERTING MEMBER THAT HAS AT LEAST ONE GROOVE OF SEMI-CIRCULAR TRANSVERSE CROSS SECTION FORMED IN THE LOWERMOST SURFACE THEREOF, MEANS FOR MOVING SAID PRESSURE-EXERTING MEMBER DOWNWARDLY RELATIVE TO SAID JAWS WITH A FORCE SUFFICIENT TO OVERCOME THE RESISTANCE OFFERED BY SAID MEANS FOR TENDING TO RESTRAIN DOWNWARD PIVOTAL MOVEMENT OF SAID JAWS, THE IMPROVEMENT FOR BENDING SAID TUBING, WHICH IMPROVEMENT COMPRISES TWO LONGITUDINALLY ALIGNED GROOVES OF NONSEMI-CIRCULAR TRANSVERSE CROSS SECTION FORMED IN THE UPPER PORTIONS OF SAID JAWS THAT ARE IN ALIGNMENT WITH SAID GROOVE IN SAID PRESSURE-EXERTING MEMBER AND OF SUCH CONFIGURATION AS TO BEND SAID TUBING WITHOUT FORMING A LONGITUDINALLY EXTENDING CREASE THEREIN AS SAID PESSUREEXERTING MEMBER IS MOVED DOWNWARDLY RELATIVE TO SAID JAWS TO PIVOT THE SAME DOWNWARDLY AND OUTWARDLY IN OPPOSITE DIRECTIONS, WITH EACH OF SAID GROOVES IN SAID JAWS BEING DEFINED BY: (A) TWO UPPER TRANSVERSELY SPACED, LONGITUDINALLY EXTENDING ARCUATE SECTIONS; (B) A LOWER CONCAVE LONGITUDINALLY EXTENDING SECTION; AND (C) TWO STRAIGHT TRANSVERSELY SPACED LONGITUDINALLY EXTENDING CHORD SECTIONS THAT EXTEND DOWNWARDLY AND INWARDLY TOWARDS ONE ANOTHER FROMTHE LOWER EXTREMITIES OF SAID UPPER ARCUATE SECTIONS TO THE UPPER EXTREMITIES OF SAID LOWER SURFACE. 